Objective: To investigate the biological roles of miR-155 in transforming growth factor-β1 (TGF-β1)-treated human prostate cancer cells PC3. Methods: PC3 cells were treated with TGF-β1. The morphological changes were observed under phase-contrast microscopy. Migration of PC3 cells was detected by Transwell assay. The expression of FN was assessed by quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting and immunofluorescence staining. miR-155 treated by TGF-β1 were analyzed by qRT-PCR. After interfering with miR-155 in TGF-β1-treated PC3 cells, qRT-PCR and Western blotting were used to detect FN expression. Migration of TGF-β1-treated PC3 cells interfered with miR-155 was detected by Transwell assay. Results: TGF-β1 treatment could induce morphological alteration of PC3 cells from compact, cobblestone morphology into spindle-shaped, fibroblast-like morphology. Transwell assay showed that TGF-β1 significantly increased the migration of PC3 cells. qRT-PCR, Western blotting and immunofluorescence staining demonstrated that TGF-β1 up-regulated the expression of FN. The expression of miR-155 induced by TGF-β1 was in a time-dependent manner. Introduction of miR-155 inhibitor partly attenuated the expression of FN in mRNA and protein levels, and inhibited the change of cell morphology and migration in TGF-β1 induced PC3 cells. Conclusion: miR-155 is up-regulated by TGF-β1 in PC3 cells, which may affect cell migration by increasing FN expression. It may have implications for treatment of human prostate cancer.